For monitoring and control in a wide range of applications, temperatures are measured for example using ceramic NTC thermistors (negative temperature coefficient thermistors), silicon temperature sensors (for example what are known as “KTY temperature sensors”), platinum temperature sensors (“PRTDs” or “platinum resistance temperature detectors”) or thermocouples (“TCs”).
For easy mounting in an application, for sufficient mechanical stability, and for protection of the actual temperature sensor element against external influences as well as for avoidance of corrosion by aggressive media, the installation is provided in housings that usually consist of plastics, of simple metal structures or of plastic/metal composites. For electrical connection, plug contacts and/or line feeds are usually integrated into the housings. Suitable sealing of such systems is provided with use of seals, potting materials and/or adhesives.
Sensor systems with plastic or polymer housings, however, cannot be used for the measurement of very high temperatures. The maximum working temperatures of such systems with plastic or polymer housings are limited to approximately 200° C. to 250° C. Metals, by contrast, which are essentially more thermally stable, have the disadvantage that complex housing shapes are difficult to produce and therefore the geometric requirements for the application usually cannot be met. Furthermore, sensor systems with metal housings can be used only to a limited extent in particularly aggressive media due to the appearance of corrosion. A further considerable disadvantage of the systems constructed in this way is the delayed response time thereof due to additional design-induced heat transfers and low thermal conductivity of the used materials.
A sensor system having a metal housing is known from document EP 2 420 807 A2.
Document JP 2010 032 237 A describes a sensor system having a ceramic sleeve.